Stallion Spotlight

BushyGeneology copy

Real Estate Spotlight

Spratt_air 1
  • Welcome to the Chronicle Forums.
    Please complete your profile. The forums and the rest of www.chronofhorse.com has single sign-in, so your log in information for one will automatically work for the other. Disclaimer: The opinions expressed here are the views of the individual and do not necessarily reflect the views and opinions of The Chronicle of the Horse.

Announcement

Collapse

Forum rules and no-advertising policy

As a participant on this forum, it is your responsibility to know and follow our rules. Please read this message in its entirety.

Board Rules

1. You�re responsible for what you say.
As outlined in Section 230 of the Communications Decency Act, The Chronicle of the Horse and its affiliates, as well Jelsoft Enterprises Ltd., the developers of vBulletin, are not legally responsible for statements made in the Forums.

This is a public forum viewed by a wide spectrum of people, so please be mindful of what you say and who might be reading it�details of personal disputes may be better handled privately. While posters are legally responsible for their statements, the moderators may in their discretion remove or edit posts, though are not legally obligated to do so, regardless of content.

Users have the ability to modify or delete their own messages after posting. Moderators generally will not delete posts, threads or accounts unless they have been alerted and have determined that a post, thread or user has violated the Forums� policies. Moderators do not regularly independently monitor the Forums for such violations.

Profanity, outright vulgarity, blatant personal insults or otherwise inappropriate statements will not be tolerated and will be dealt with at the discretion of the moderators.

Users may provide their positive or negative experiences with or opinions of companies, products, individuals, etc.; however, accounts involving allegations of criminal behavior against named individuals or companies MUST be first-hand accounts and may NOT be made anonymously.

If a situation has been reported upon by a reputable news source or addressed by law enforcement or the legal system it is open for discussion, but if an individual wants to make their own claims of criminal behavior against a named party in the course of that discussion, they too must identify themselves by first and last name and the account must be first-person.

Criminal allegations that do not satisfy these requirements, when brought to our attention, may be removed pending satisfaction of these criteria, and we reserve the right to err on the side of caution when making these determinations.

Credible threats of suicide will be reported to the police along with identifying user information at our disposal, in addition to referring the user to suicide helpline resources such as 1-800-SUICIDE or 1-800-273-TALK.

2. Conversations in horse-related forums should be horse-related.
The forums are a wonderful source of information and support for members of the horse community. While it�s understandably tempting to share information or search for input on other topics upon which members might have a similar level of knowledge, members must maintain the focus on horses.

3. Keep conversations productive, on topic and civil.
Discussion and disagreement are inevitable and encouraged; personal insults, diatribes and sniping comments are unproductive and unacceptable. Whether a subject is light-hearted or serious, keep posts focused on the current topic and of general interest to other participants of that thread. Utilize the private message feature or personal email where appropriate to address side topics or personal issues not related to the topic at large.

4. No advertising in the discussion forums.
Posts in the discussion forums directly or indirectly advertising horses, jobs, items or services for sale or wanted will be removed at the discretion of the moderators. Use of the private messaging feature or email addresses obtained through users� profiles for unsolicited advertising is not permitted.

Company representatives may participate in discussions and answer questions about their products or services, or suggest their products on recent threads if they fulfill the criteria of a query. False "testimonials" provided by company affiliates posing as general consumers are not appropriate, and self-promotion of sales, ad campaigns, etc. through the discussion forums is not allowed.

Paid advertising is available on our classifieds site and through the purchase of banner ads. The tightly monitored Giveaways forum permits free listings of genuinely free horses and items available or wanted (on a limited basis). Items offered for trade are not allowed.

Advertising Policy Specifics
When in doubt of whether something you want to post constitutes advertising, please contact a moderator privately in advance for further clarification. Refer to the following points for general guidelines:

Horses � Only general discussion about the buying, leasing, selling and pricing of horses is permitted. If the post contains, or links to, the type of specific information typically found in a sales or wanted ad, and it�s related to a horse for sale, regardless of who�s selling it, it doesn�t belong in the discussion forums.

Stallions � Board members may ask for suggestions on breeding stallion recommendations. Stallion owners may reply to such queries by suggesting their own stallions, only if their horse fits the specific criteria of the original poster. Excessive promotion of a stallion by its owner or related parties is not permitted and will be addressed at the discretion of the moderators.

Services � Members may use the forums to ask for general recommendations of trainers, barns, shippers, farriers, etc., and other members may answer those requests by suggesting themselves or their company, if their services fulfill the specific criteria of the original post. Members may not solicit other members for business if it is not in response to a direct, genuine query.

Products � While members may ask for general opinions and suggestions on equipment, trailers, trucks, etc., they may not list the specific attributes for which they are in the market, as such posts serve as wanted ads.

Event Announcements � Members may post one notification of an upcoming event that may be of interest to fellow members, if the original poster does not benefit financially from the event. Such threads may not be �bumped� excessively. Premium members may post their own notices in the Event Announcements forum.

Charities/Rescues � Announcements for charitable or fundraising events can only be made for 501(c)(3) tax-exempt organizations. Special exceptions may be made, at the moderators� discretion and direction, for board-related events or fundraising activities in extraordinary circumstances.

Occasional posts regarding horses available for adoption through IRS-registered horse rescue or placement programs are permitted in the appropriate forums, but these threads may be limited at the discretion of the moderators. Individuals may not advertise or make announcements for horses in need of rescue, placement or adoption unless the horse is available through a recognized rescue or placement agency or government-run entity or the thread fits the criteria for and is located in the Giveaways forum.

5. Do not post copyrighted photographs unless you have purchased that photo and have permission to do so.

6. Respect other members.
As members are often passionate about their beliefs and intentions can easily be misinterpreted in this type of environment, try to explore or resolve the inevitable disagreements that arise in the course of threads calmly and rationally.

If you see a post that you feel violates the rules of the board, please click the �alert� button (exclamation point inside of a triangle) in the bottom left corner of the post, which will alert ONLY the moderators to the post in question. They will then take whatever action, or no action, as deemed appropriate for the situation at their discretion. Do not air grievances regarding other posters or the moderators in the discussion forums.

Please be advised that adding another user to your �Ignore� list via your User Control Panel can be a useful tactic, which blocks posts and private messages by members whose commentary you�d rather avoid reading.

7. We have the right to reproduce statements made in the forums.
The Chronicle of the Horse may copy, quote, link to or otherwise reproduce posts, or portions of posts, in print or online for advertising or editorial purposes, if attributed to their original authors, and by posting in this forum, you hereby grant to The Chronicle of the Horse a perpetual, non-exclusive license under copyright and other rights, to do so.

8. We reserve the right to enforce and amend the rules.
The moderators may delete, edit, move or close any post or thread at any time, or refrain from doing any of the foregoing, in their discretion, and may suspend or revoke a user�s membership privileges at any time to maintain adherence to the rules and the general spirit of the forum. These rules may be amended at any time to address the current needs of the board.

Please see our full Terms of Service and Privacy Policy for more information.

Thanks for being a part of the COTH forums!

(Revised 5/9/18)
See more
See less

Differences in gene expression in embryos seen when frozen semen is used

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Differences in gene expression in embryos seen when frozen semen is used

    Things aren't quite as simple as we believed.


    Interesting study that is available on PLoS One here: ]https://journals.plos.org/plosone/ar...l.pone.0213420 And summarized here: https://www.horsetalk.co.nz/2019/06/...-frozen-semen/

    Here's the complete discussion section:
    Discussion

    Here we report, for the first time, evidence that procedures performed during handling of sperm, such as freezing and thawing, have a significant impact on critical aspects of the early embryo transcriptome. The equine model used in our study has a number of advantages, including a long pre-attachment embryonic period in which the embryo remains spherical, which facilitates embryo collection, and the possibility of repeated embryo collections from the same animals over successive estrus cycles. Additionally, the stallion serves as an excellent model for the human male, as stallions are typically not selected for sperm quality nor the ability of semen to be cryopreserved, in contrast to males in production species, such as the bull. Moreover, since many stallions reach advanced age, the horse can be used as a model to study the impact of paternal age on embryo quality.

    Our study, focused on three embryo ages (8, 10 and 12 days post ovulation), revealed a significant impact of sperm cryopreservation on the transcriptome of the resulting embryo. Importantly, transcripts with decreased abundance reflected genes related to DNA replication and assembly, and oxidative phosphorylation. Exploration of differentially-expressed genes at the molecular and cellular level revealed alterations in important functions including ATP synthesis, regulation of transcription, nucleosome assembly, chromatin silencing, protein synthesis, and redox regulation. Alterations in these genes help to explain the reduced fertility observed with cryopreserved sperm attributable to increased early embryo mortality [11, 12].

    The pre-implantation period is a period of rapid embryo growth, requiring a ready supply of ATP. The equine embryo appears to have a significant capacity for glycolysis, but also uses oxidative phosphorylation [36]. The KEGG pathways analysis of downregulated genes revealed enriched annotations for oxidative phosphorylation, pyruvate metabolism, glycolysis, and the TCA cycle, suggesting compromised energy metabolism in CRYO embryos. A similar picture was observed in Day-10 and Day-12 embryos, with the pathways for oxidative phosphorylation, metabolic pathways, and non alcoholic fatty liver disease significantly over-represented in transcripts with reduced abundance of all CRYO embryos obtained.

    When we evaluated low-abundance equine transcripts for their mouse orthologs, we found that many of the genes downregulated in CRYO embryos have knockout database annotation terms related to reduced embryonic viability. This finding opens the possibility that not only genes related to the metabolism and thus growth of embryos, but also genes directly related to embryo organogenesis, embryo survival, and offspring health are affected by the use of cryopreserved sperm, and thus these genes warrant further investigation.

    While the mechanisms behind the effects reported here are as yet unclear, a major factor may be the well-documented oxidative damage that the genome and epigenome experiences during cryopreservation and thawing [1114]. Cryopreservation is a major cause of oxidative stress [37] and lipid peroxidation in stallion spermatozoa [10, 17, 38, 39]. Lipid peroxidation in spermatozoa surviving cryopreservation [37] is associated with increased levels of 4-hydroxinonenal (4-HNE) [17]. This compound is able to interact with DNA to form adducts that have been related directly to increased rates of mutation in important cell-cycle regulators [40, 41]. The production of 4-HNE during cryopreservation of stallion spermatozoa is well documented [10, 17, 39], and it is possible that significant amounts of 4-HNE and other toxic lipid aldehydes are incorporated to the oocyte, potentially causing alterations in embryo development. In addition to DNA damage, 4-HNE can alkylate the sperm centrioles, and in horses, as in humans, paternal centrioles are inherited by the embryos. Damaged centrioles may cause disrupted cytoskeletal protein organization during early cleavage [42].

    Supporting this line of reasoning, recent reports have linked abnormal early cleavage events and changes in embryo transcript abundance to fertilization with spermatozoa showing oxidative stress. Macaque embryos obtained after fertilization with ROS-treated sperm showed significantly lower rates of development to the four- and eight-cell stages, and changes in transcript abundance for genes related to actin cytoskeleton organization, cell junction assembly and cell adhesion [43]. Although seen at a much later stage of development, in our study we also found that genes for cytoskeleton components tubulin alpha 1 a, tubulin beta 2 class II a and actin, cytoplasmic 1, N-terminally processed were downregulated in 8-day CRYO embryos.

    Cryopreservation may also directly affect the epigenome of the paternal DNA; recent studies have shown that cryopreservation increases the level of DNA methylation in equine sperm [12] and the expression of genes important to intracellular regulation of epigenetic status [16]. Notably, we also found significant reduction in abundance of transcripts for histones in CRYO embryos.

    The finding that many differentially regulated genes in CRYO embryos are orthologs of mouse genes that have knockout database annotation terms related to reduced embryonic viability provides further evidence linking cryopreserved sperm to reduced embryonic viability. These annotations consistently appeared on analysis of low-abundance transcripts in all CRYO embryos, and included genes related to embryonic growth retardation and embryo lethality. Interestingly, annotations related to male and female infertility were also present; this warrants further investigation on the effect of sperm origin on the fertility of resulting offspring.

    In summary, the present study provides for the first time transcriptomic analysis of equine embryos in relation to the handling of semen used for their production, however we acknowledge the preliminary and descriptive nature of this report but our data provide strong evidence that cryopreservation of sperm exerts a profound impact on the transcriptome of early embryos. Our findings may stimulate new lines of research to improve this biotechnology in humans and animals.
    Last edited by vineyridge; Jun. 29, 2019, 02:51 PM.

  • #2
    Very interesting! Does this mainly affect the viability of the embryo, or are there health consequences for the foal/horse?

    To me it reads like the main question is viability of the embryo, but am I missing something?

    Comment


    • #3
      Those are my questions as well. Hopefully that means that the embryo is more likely to fail when created with frozen but if carried to term will go on to be the same horse as they would have been if fresh semen had been used.
      McDowell Racing Stables

      Home Away From Home

      Comment

      • Original Poster

        #4
        The article does say this:

        Moreover, appreciation of the contribution of sperm to embryo development has evolved from the concept that the only role of sperm at fertilization is to introduce the male genome into the egg. Sperm carry a myriad of small noncoding RNAs with potential roles in early embryo development [21, 22]. Notably, sperm carry the activating factor PLCζ, which triggers calcium oscillations that induce oocyte activation [23, 24], and it has been shown in mouse and rabbit that alterations in frequency and amplitude of post-fertilization calcium oscillations can affect the phenotype of the resulting embryo into post-implantation development and adulthood [25, 26]. Thus, there are extensive pathways by which cryopreservation of sperm could alter the development of the fertilized oocyte and embryo.
        So at this point in time it would seem to be an open question whether a foal is different if produced by frozen semen.

        Comment


        • #5
          Sooooooo cool, I can't wait to read the whole article. Thank you!!!!!!!!!
          Proud member of the Colbert Dressage Nation

          Comment

          Working...
          X